Field
Embodiments of the present disclosure relate to apparatus and methods for processing semiconductor substrates. More particularly, embodiments of the present disclosure relate to a process chamber having modular design to provide variable process volume and improved flow conductance and uniformity.
Description of the Related Art
Electronic devices, such as flat panel displays and integrated circuits, commonly are fabricated by a series of processes in which layers are deposited on a substrate and the deposited material is etched into desired patterns. The processes commonly include physical vapor deposition (PVD), chemical vapor deposition (CVD), plasma enhanced CVD (PECVD), and other plasma processing. Specifically, a plasma process includes supplying a process gas mixture to a vacuum chamber, and applying radio frequency power (RF power) to excite the process gas into a plasma state. The plasma decomposes the gas mixture into ion species that would perform the desired deposition or etch processes.
One problem encountered during plasma processes is the difficulty associated with establishing uniform plasma density over the substrate surface during processing, which leads to non-uniform processing between the center region and the edge regions of a substrate. The difficulty in establishing uniform plasma density may be contributed by skews in natural electrical current, gas flow, and thermal distribution due to asymmetries in the physical process chamber design. Such skews not only result in non-uniform plasma density, but also make it difficult to use other processing variables or “knobs” to control center-to-edge plasma uniformity.
Optimal process parameters, such as process volume, distance between a substrate and a gas distribution showerhead, are generally different for different processes. For example, different process volumes are desirable when etching a conductor layer, etching a dielectric layer or stripping a photoresist layer. To satisfy different processes, multiple process chambers may be needed, which increases cost of ownership.
Therefore, there is a need for a process chamber that enables variable process volume, improved flow conductance, and improved process uniformity.